This invention relates a method and apparatus for stacking cartons and more particularly, to straddles that connect to a carton for holding one carton stacked on another carton during movement on a conveyor and/or while being stacked onto a pallet.
Cartons commonly used in the produce industry to hold fruits and vegetables are of a two-piece variety designed to facilitate hand packing. One piece is a box without a top. This piece is for packing a given quantity of the produce by a packer. The second piece of the carton is a box without a bottom whose dimensions are slightly larger than the first piece, and which is designed to be slipped over the packed first piece. Typically, the cartons are available in two standard sizes; one that holds 4/5 of a bushel and a second, half carton size that holds 2/5 of a bushel. The half carton is usually considered a "gift pack" promoted by organizations making fund drives--churches, schools, Boy Scouts, etc.
In conveying the half cartons, the same amount of space is required as for the full carton (4/5 bushel). Thus, only half the volume of produce is being transported. The same holds true for stacking the product manually or on an automatic palletizer; the smaller carton requires twice the number of cartons to form a pallet or unit load for shipment, and running the smaller cartons can easily reduce production 50%. To move the same volume of produce can require extra packinghouse operating hours, since produce is a perishable commodity and time is of essence in a packinghouse operation. Therefore, a packing operation that utilizes the straddle technique to "piggyback" cartons being conveyed to a shipping area can increase volume. In the case of stacking cases on a pallet (by hand or automatic palletizing), a 100% increase in production is realized.